CMOS – Shutterless Operation Boosts Speed and Quality

CMOS technology based X-ray detectors offer numerous advantages compared to traditionally used CCD detectors: · CMOS sensors are available in larger sizes with a pixel size optimized for X-ray scattering and X-ray diffraction. · CMOS sensors have lower power consumption than CCDs and provide excellent signal-to-noise ratios even when only moderately cooled. This allows the design of air-cooled detectors. Both, low power consumption and no need for cooling-water, lead to minimized pre-installation requirements. · While CCDs use a bucket brigade read-out, CMOS technology does allow continuous direct sensor read-out. These features make modern CMOS based X-ray detectors, such as the PHOTON 100, an excellent solution for single crystal X-ray diffraction (SC-XRD) experiments. In particular, the capability to continually read out pixels provides a new approach for data collection. While CCDs require closing the shutter for each read-out step, introducing system overhead, CMOS based detectors can be operated in shutterless mode, which not only eliminates over-head time but it also reduces mechanical jitter. We will present details on the implementation of shutterless readout in the current state-of-the-art SC-XRD instrumentation, the D8 QUEST and D8 VENTURE systems. Furthermore, the impact of shutterless read-out on data quality and data collection speed will be discussed using examples from chemical crystallography and structural biology.

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Dynamic X-ray diffraction sampling for protein crystal positioning

Journal of Synchrotron Radiation ◽

10.1107/s160057751601612x ◽

2017 ◽

Vol 24 (1) ◽

pp. 188-195 ◽

Cited By ~ 9

Author(s):

Nicole M. Scarborough ◽

G. M. Dilshan P. Godaliyadda ◽

Dong Hye Ye ◽

David J. Kissick ◽

Shijie Zhang ◽

...

Keyword(s):

Image Reconstruction ◽

Data Collection ◽

Argonne National Laboratory ◽

Ground Truth ◽

Protein Crystal ◽

X Ray Diffraction ◽

X Ray ◽

Raster Scanning ◽

Dynamic Sampling ◽

The Impact

A sparse supervised learning approach for dynamic sampling (SLADS) is described for dose reduction in diffraction-based protein crystal positioning. Crystal centering is typically a prerequisite for macromolecular diffraction at synchrotron facilities, with X-ray diffraction mapping growing in popularity as a mechanism for localization. In X-ray raster scanning, diffraction is used to identify the crystal positions based on the detection of Bragg-like peaks in the scattering patterns; however, this additional X-ray exposure may result in detectable damage to the crystal prior to data collection. Dynamic sampling, in which preceding measurements inform the next most information-rich location to probe for image reconstruction, significantly reduced the X-ray dose experienced by protein crystals during positioning by diffraction raster scanning. The SLADS algorithm implemented herein is designed for single-pixel measurements and can select a new location to measure. In each step of SLADS, the algorithm selects the pixel, which, when measured, maximizes the expected reduction in distortion given previous measurements. Ground-truth diffraction data were obtained for a 5 µm-diameter beam and SLADS reconstructed the image sampling 31% of the total volume and only 9% of the interior of the crystal greatly reducing the X-ray dosage on the crystal. Using in situ two-photon-excited fluorescence microscopy measurements as a surrogate for diffraction imaging with a 1 µm-diameter beam, the SLADS algorithm enabled image reconstruction from a 7% sampling of the total volume and 12% sampling of the interior of the crystal. When implemented into the beamline at Argonne National Laboratory, without ground-truth images, an acceptable reconstruction was obtained with 3% of the image sampled and approximately 5% of the crystal. The incorporation of SLADS into X-ray diffraction acquisitions has the potential to significantly minimize the impact of X-ray exposure on the crystal by limiting the dose and area exposed for image reconstruction and crystal positioning using data collection hardware present in most macromolecular crystallography end-stations.

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The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

Scientific Reports ◽

10.1038/s41598-021-81017-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mikolaj Grabowski ◽

Ewa Grzanka ◽

Szymon Grzanka ◽

Artur Lachowski ◽

Julita Smalc-Koziorowska ◽

...

Keyword(s):

Quantum Wells ◽

High Temperatures ◽

Point Defects ◽

X Ray Diffraction ◽

Helium Ions ◽

X Ray ◽

Sapphire Substrates ◽

Transmission Electron ◽

The Impact ◽

Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

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Ionic conductivity in nanocrystalline Gd doped ceria

MRS Proceedings ◽

10.1557/proc-1122-o06-02 ◽

2008 ◽

Vol 1122 ◽

Cited By ~ 1

Author(s):

Gianguido Baldinozzi ◽

David Simeone ◽

Dominique Gosset ◽

Mickael Dollé ◽

Georgette Petot-Ervas

Keyword(s):

Grain Size ◽

Ionic Conductivity ◽

Sol Gel ◽

Doped Ceria ◽

Narrow Size Distribution ◽

Conductivity Measurements ◽

X Ray Diffraction ◽

X Ray ◽

Grain Sizes ◽

The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

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Lanthanoid Complexes Supported by Retro-Claisen Condensation Products of β-Triketonates

10.26434/chemrxiv.6448253.v3 ◽

2018 ◽

Author(s):

Laura Abad Galán ◽

Alexandre N. Sobolev ◽

Eli Zysman-Colman ◽

Mark Ogden ◽

Massimiliano Massi

Keyword(s):

Chelating Ligands ◽

X Ray Diffraction ◽

Reaction Conditions ◽

Claisen Condensation ◽

X Ray ◽

Condensation Products ◽

Complexation Reactions ◽

The Impact ◽

Low Solubility

β-Triketonates have been recently used as chelating ligands for lanthanoid ions, presenting unique structures varying from polynuclear assemblies to polymers. In an effort to overcome low solubility of the complexes of tribenzoylmethane, four β-triketones with higher lipophilicity were synthesised. Complexation reactions were performed for each of these molecules using different alkaline bases in alcoholic media. X-ray diffraction studies suggested that the ligands were undergoing decomposition under the reaction conditions. This is proposed to be caused by in situretro-Claisen condensation reactions, consistent with two examples that have been reported previously. The lability of the lanthanoid cations in the presence of a varying set of potential ligands gave rise to structures where one, two, or three of the molecules involved in the retro-Claisen condensationreaction were linked to the lanthanoid centres. These results, along with measurements of ligand decomposition in the presence of base alone, suggest that using solvents of lower polarity will mimimise the impact of the retro-Claisen condensation in these complexes.

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Influence of the Para-Substituent in Lanthanoid Complexes of Bistetrazole Substituted Calix[4]arenes

10.26434/chemrxiv.9255209 ◽

2019 ◽

Author(s):

Rene Z.H. Phe ◽

Brian Skelton ◽

Massimiliano Massi ◽

Mark Ogden

Keyword(s):

Structural Changes ◽

Cluster Formation ◽

Ammonium Cation ◽

Ammonium Salts ◽

X Ray Diffraction ◽

One Dimensional ◽

X Ray ◽

Mononuclear Complexes ◽

Scattering Measurements ◽

The Impact

5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the para substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with p-H, and p-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the p-H and p-allyl derivatives, in contrast with the behaviour of the t-butyl analogue. Lanthanoid complexes of the p-H and p-allyl calixarenes were characterised by single crystal X-ray diffraction, and were found to form mononuclear complexes, linked to form a one-dimensional coordination polymer for the p-allyl system. All of the complexes were isolated as ammonium salts, with ammonium cation included in the calixarene cavity in most cases. It is concluded that the nature of the para substituent has a profound impact on the lanthanoid cluster formation process, and derivatives with more subtle structural changes will be required to determine if additional lanthanoid “bottlebrush” clusters can be isolated.

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Experimental Investigation on Intensity and Residual Stress in Superficial Layers Induced by Water Cavitation Peening with Aeration

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.373-374.754 ◽

2008 ◽

Vol 373-374 ◽

pp. 754-757 ◽

Cited By ~ 1

Author(s):

Dong Ying Ju ◽

B. Han

Keyword(s):

Residual Stress ◽

Process Capability ◽

Diffraction Method ◽

Spring Steel ◽

Bubble Collapse ◽

Process Conditions ◽

X Ray Diffraction ◽

X Ray ◽

Enhancement Method ◽

The Impact

Water cavitation peening (WCP) with aeration is a novel surface enhancement method. A new ventilation nozzle with aeration is adopted to improve the process capability of WCP by increasing the impact pressure induced by the bubble collapse on the surface of components. In this study, in order to investigate the process capability of the WCP with aeration, a standard N-type almen strips of spring steel SAE 1070 was treated by WCP with various process conditions, and the arc height value and the residual stress in the superficial layers were measured by X-ray diffraction method. The optimal fluxes of aeration and the optimal standoff distances were achieved.

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Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

Journal of Applied Crystallography ◽

10.1107/s1600576719014705 ◽

2020 ◽

Vol 53 (1) ◽

pp. 27-33

Author(s):

Ziwei Lai ◽

Shuailin Zhang ◽

Nan Zheng ◽

Shichen Yu ◽

Masaki Ageishi ◽

...

Keyword(s):

Hierarchical Structure ◽

Phase Cell ◽

X Ray Diffraction ◽

X Ray ◽

Hierarchical Nanostructure ◽

Α Phase ◽

Triclinic Symmetry ◽

Phase Crystal ◽

Unit Cells ◽

The Impact

It has been recognized that macromolecular chains can self-assemble into a hierarchical structure from lamellae to spherulites in bulk crystallization. However, little account has been taken of crystal symmetry effects on the hierarchical nanostructure in polymers under cylindrical confinement. In this research, a model polymer, nylon 6,12, most commonly occurring in the triclinic α phase, was chosen in order to demonstrate the effect of triclinic symmetry on the 2D-constrained polymer nanostructure. The self-arranging unit of nylon 6,12 takes various forms, including stems, unit cells, hydrogen-bonded sheets, lamellae and complex spherulites, which is an essential structural feature for investigating hierarchical nanostructure. The rod nanostructure in confinement was examined by cross-checking electron and X-ray diffraction techniques. It is found that the a* axis of the α-phase cell is inclined at about ±6–11° to the rod long axis within the a*b* plane around the c axis (c axis ⊥ rod long axis). The rotation of the a*b* plane most likely results from the impact of the triclinic symmetry on the molecular chain packing under 2D confinement. A mechanism for this a*b* plane tilting is proposed.

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Influence of Iron Bacteria on the Corrosion Behavior of Carbon Steel: SEM Study

Jurnal Teknologi ◽

10.11113/jt.v65.1328 ◽

2013 ◽

Vol 65 (1) ◽

Author(s):

E. Hamzah ◽

C. L. Khohr ◽

Ahmad Abdolahi ◽

Z. Ibrahim

Keyword(s):

Carbon Steel ◽

Cooling Water ◽

Low Carbon Steel ◽

Iron Hydroxides ◽

Low Carbon ◽

X Ray Diffraction ◽

X Ray ◽

Iron Bacteria ◽

Microbially Influenced Corrosion ◽

Sem Study

In this work, the iron bacteria were cultured and inoculated into the cooling water before immersion, and low carbon steel coupons were immersed for one month. Then, microbially influenced corrosion (MIC) of carbon steel in the presence of these bacteria was investigated using scanning electron microscopy (SEM), x-ray diffraction spectroscopy (XRD) and weight loss methods. SEM results showed that large amounts of corrosion products and heterogeneous biofilm layer were formed on the coupon surface. SEM also revealed the uniform-pitting corrosion on the steel surface due to bacteria colonization. XRD results show that the main constituents present in corrosion product are composed of iron oxides and iron hydroxides.

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E. S. Fedorov Promoting the Russian-German Scientific Interrelationship

Minerals ◽

10.3390/min10020181 ◽

2020 ◽

Vol 10 (2) ◽

pp. 181 ◽

Cited By ~ 1

Author(s):

Peter Paufler ◽

Stanislav K. Filatov

Keyword(s):

Crystal Structure ◽

Crystal Structures ◽

Structure Analysis ◽

Crystalline State ◽

Crystal Structure Analysis ◽

Present Knowledge ◽

Personal Contact ◽

X Ray Diffraction ◽

X Ray ◽

The Impact

At the dawn of crystal structure analysis, the close personal contact between researchers in Russia and Germany, well documented in the “Zeitschrift für Krystallographie und Mineralogie”, contributed significantly to the evolution of our present knowledge of the crystalline state. The impact of the Russian crystallographer E. S. Fedorov upon German scientists such as A. Schoenflies and P. Groth and the effect of these contacts for Fedorov are highlighted hundred years after the death of the latter. A creative exchange of ideas paved the way for the analysis of crystal structures with the aid of X-ray diffraction.

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Imidazole-containing Bispidine Ligands: Synthesis, Structure and Cu(II) Complexation

Zeitschrift für Naturforschung B ◽

10.1515/znb-2011-0713 ◽

2011 ◽

Vol 66 (7) ◽

pp. 721-728 ◽

Cited By ~ 2

Author(s):

Martin Walther ◽

Madlen Matterna ◽

Stefanie Juran ◽

Silke Fähnemann ◽

Holger Stephan ◽

...

Keyword(s):

Solid State ◽

Nmr Spectroscopy ◽

Enol Form ◽

Trans Configuration ◽

X Ray Diffraction ◽

X Ray ◽

The Impact ◽

Configurational Isomerism

The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state.

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